Intermediate pressure take-off from barrel type boiler feed pumps



Feb. 16, 1960 M. w. LUTZ 2,925,042

I INTERMEDIATE PRESSURE TAKE-OFF FROM BARREL TYPE BOILER FEED PUMPS Filed Dec. 9, 1957 2 Sheets-Sheet 1 Feb 16, 19% M. w. LUTZ 2,925,042

INTERMEDIATE PRESSURE TAKE-OFF FROM BARREL TYPE BOILER FEED PUMPS Filed Dec 9 1957 2 Sheets She t 2 pressure.

United States Patent INTERMEDIATE PRESSURE TAKE-OFF FROM BARREL TYPE BOILER FEED PUMPS Milton W. Lutz, Wanwatosa, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

' Application December 9, 1957, Serial No. 701,413

3 Claims. (Cl. 103-108) through a relatively movable member as was done in the prior art.

An object of this invention is to provide new and improved means for obtaining fluid from any stage of a double casing multiple stage centrifugal machine.

' Another object of this invention is to provide a new and improved leakless intermediate fluid take-oflf in double casing multiple stage centrifugal machines.

Another object of this invention is to provide a new and improved intermediate fluid take-01f in double casing multiple stage centrifugal machines that is easy to assemble.

Objects and advantages other than those above set forth will be apparent as the description of the invention proceeds.

The novel features of the invention and how the objects are obtained will appear from the following deoftenused as aboiler feed pump in power houses. It is desirable in power houses to have available fluid at a pressure other than the high terminal pressure obtained from double casing multiple stage pumps. In the past, this has been done by providing an auxiliary pump to generate the desired pressure, or by tapping through the double casing, to the pump stage generating the desired pressure. A leakage problem was encountered when tapping fluid from an intermediate stage of a multiple stage pump because the relative movement between the inner and outer casing made it difficult to adequately seal the conduit carrying the fluid at intermediate pressure where it passes through the outer casing.

. The relative movement between the inner and outer casing is duefto the outer casing being subjected to high discharge pressure to its inner side and to atmospheric pressure to its. outer side; Therefore, while the pump is operating, the outer casing distorts in an outward direction. On the other hand, the inner casing is subjected to the high discharge pressure of the pump on its outer side, and on its inner side, is subjected to pressures that 1 and scription and the accompanying drawings showing an embodiment or the invention and forming a part of this application and all these novel features are intended to be pointed out in the claims.

In the drawings:

Fig. 1 is a longitudinal section of a portion of a double casing multiple stage centrifugal pump embodying the invention;

Fig. 2 is a cross section of Fig. 1 taken at line II-II;

Fig. 3 is a cross section of Fig. 1 taken at line III-III.

The pump as shownin Fig. 1 is of usual double casing design similar to the pump described in US. Patent 2,668,502, E. J. Blackwell, issued February 9, 1954. The double casing multiple stage centrifugal pump emvary at each pumping stage, but certainly much above atmospheric pressure. Because of the design and the inherent high compression strength of the casing material, theinner casing has relatively good resistance to deformatio'ri as compared to the outer casing. The pressure differential on the inner casing is much less than on the outer casing. The pressure diiferential that does exist results in a squeezing effect, and because the casing material has high compression strength, the inner casing will remain relatively stationary whilethe pump is operating.

The result of all the forces, acting on the casings is to cause the outer casing toexpand and to move outward relative to the inner casing while the pump is operating.

In the pumpof this invention, an annular member hereinafter called a stufling ,box, surrounds the shaft and is attachedto the inner casing. The stuifing box, therefore, is stationary relative to the inner casing. The outer casing is slidably mounted on the stuffing box to ,allow rnovement relative to the inner casing. The stufiing box is provided with a passageway extending therethrough that connects thear'ea. between the inner and outer casings tg the atmosphere. A port is provided in the volute of any pumping stage to withdraw fluid at an intermediate A conduit extends in the area between the inner and outer casing and connects the port to the inboard end of the passageway in the stufling box. Means are provided at the outboard end of the passageway in the stufiing box for receiving and distributing the fluid from the intermediate pressure stage. Hence the inter mediate pressure conduit extends from one member through a relatively stationary member rather than bodying the invention comprises an outer casing 1, an outer casing cover 2, an inner casing 3, a series of pumping stages such as 4, 5, 6, 7, 20 and a stufiing box 8.

The outer casing 1 is opened at oneend 12andhas an inlet (not shown) and outlet 9. A casing cover 2 defining a centrally located aperture 11 is removably attachedto the open end 12 of outer casing 1.

The inner casing 3 is mounted in the outer casing 1. The, inner casing 3 has an inlet (not shown) and an outlet 13 which are aligned with and communicate respectively with the inlet (not shown) and outlet 9 of the outer casing 1. As shown in Fig. 1,"the inner casing 3 is also provided with a series of annular passageways or volutes, such as 13, 16, 17, 18, and 19 that form pump stages 4, 5, 6, 7, and 20. All the stages of the pump are hydraulically connected in a successive series, for ex: ample, the discharge 55 of stage 5 enters the inlet 66 of stage 6 and, so on to the next successive stage until the terminal stage 20 is reached. i

A shaft 14 is rotatably mounted in the inner casing 3 and extends through the aperture 11 in the cover 2. Impellers 15 are mounted on the'shaft 14 for rotation therewith and are operatively disposed to rotate within the volutes such as 13, 16, 17, 18, 1? of the inner casing 3. The impellers 15 transmit the fluid from the inlet of the first stage (not shown) at inlet pressure through the axially spaced and hydraulically connected stages to the terminal stage 20, successively increasing the pressure in each stage.

Suitable means are provided to support the inner casing 3 in proper axial alignment relative to the outer casing '1. In-the preferred embodiment of this invention, "as shown in Fig. 1, a stufiing box 8 surrounds the shaft 14 to seal the shaft 14 to the inner casing 3 and to maintain the inner casing 3 in proper axial alignment with the outer casing 1. The stuffing box 3 is attached to the inner casing 3 by suitable means such as by bolts 28 and is positioned in the aperture 11 of the cover 2. The cover 2 is slidably mounted on the stuffing box 8 and packing means 29 are positioned between the stuffing 7 area intermediate sa1d comprising:

the cover 2 to insure a liquid tight seal. This arrangement allows axial expansion of theouter casing 1 relative to mner casing 3 in response to the changes in pressure and/ or temperatures within the "out-er 1 casing- 1.

To obtain fluid at intermediate pressure, a port 21 is prov ded in the discharge-volute of an intermediate pumpngstage' such as-the volute 55 of stage 5. r This port 21 is provided with means to receive conduit 22. A passageway 23 is defined in stufling box 8 and .eonn'ectsrthe area intermediate the casings to the atmosphere. The inboard end 24 of passageway 23 is provided with means to rece ve the conduit 22. The conduit 22 connects the port 21 to the inboard end 24 of passageway23. 'The condurt 22' may be provided with coupling means 26 interrnedrate its ends for ease in assembling ortoallow fluid to be withdrawn from'other pumping -stages.' '1l?he conduit 22 connecting the port 21 and the inboard end 24 of the passageway 23 extends in the area between the inner and outer casings as shown in Fig. 2.

A discharge conduit 27 is connected to the outboard end 25 of the passageway 23 in the stufling box 8, and

suitable external means are provided for receiving and distributing the withdrawn fluid.

In operation, fluid at desiredpressure, passes from the discharge volute 55 through the port 21 into the conduit 22 henceinto the passageway 23 of stuffing box 8. It passes through the passageway 23, being received bythe 4 and spaced from said outer casing, said inner casing having an inlet and outlet communicating respectively with said outer casing inlet and outlet; pumping means within said inner casing, said pumping means including a predetermined number of hydraulically connected volutes to transport the fluid from said inlet to said outletgra shaft rotatably disposed within said inner casing, said shaft extendingaxially through one end 'of "said outercasing; impellers mounted on said shaft for rotation therewith and positionable within said volutes to transmit the fluid from said inlet to said outlet; astufling box surrounding said shaft and attached to said inner casing, said stuffing box positioned within said oneend ofysaidouterI-casing to align said inner andouter casings,v said outericasing being slidably mounted on said stuffing box; packing means to seal said shaft to said stufling box and said outer casing to said stuflflng box; and means to withdraw fluid at an intermediate pressure from saidpump, said means.

comprising a port located in an intermediate said volute, a passageway extending through said'stufling box connecting the area'intermediate said casings to theatmosp here, a conduit extending in the area betweensaid inner and outer casings connecting said port to the inboard end o f said passageway, and means connected to the outboard discharge conduit 27 having means to receive and distribute the fluid withdrawn, p

The volume of fluid withdrawn from the intermediate stage will be limited by the'respective-sizes of the port, the conduit and the passageway.

, It is understood that the foregoing illustrative description is intended to definitely exemplify applicants invention and is in no way intended to limit the scope thereof other than as may be reflected in the'terms of the claims appended hereto.

What-is claimed is: p t I 1. A double casing multiple stage centrifugal machine comprising: an outer casing having an inlet and outlet; an inner casing disposed within and spaced from said outer casing, said inner casing having an inlet and outlet communicating respectively with said outer casing inlet and outlet; a series of axially spaced and connected volutes within said inner casing to transport fluid from said'inlet to said outlet; a shaft rotatably disposed within said inner casing, said shaft extending axially through one end'of said outer casing; impellers mounted on said shaft for rotation therewith and positionable in said yolutes to propel the fluid from said inlet to "said outlet; fa stufling box surrounding said shaft and attached to said inner casing, said outer casing slidably mounted on said fstufling box, and packing means to seal said s haft and said outer casing to said stuffing box; and means to withdraw fluid from an intermediate saidvolute,-said means comprising said intermediate volute having a port defined therein connecting said intermediate ,voluteto the casings, a' passageway defined in end-of said passageway for receiving and distributingsaid withdrawn'fluid. a V a a I t 3; A double casing multiple stage centrifugal pump comprising: anouter casing open at oneend and having an :inlet and an outlet; -a cover suitably mountedion said outer casing and defining a centrally located aperture; an inner casingmounted within and spaced from said outer casing, said inner casing havingan inlet and :an outlet communicating respectively with said 'in'letfand outlet of saidouter casing andia plurality of axially spaced voluteshydraulically connected in series to form pump stages;ashaftrotatably mounted within said inner casing, said shaft extending axially thr o'ug'hisaid aperture in said cover; a series'of axiallyspacedimpellers mounted on said shaft for rotation therewith and positionable within said volutes to transmitthe fluid fromsaid inlet I said coverand surrounding saidshaftapackingmeansto said stufling box connecting'the area intermediate said casings to the atmosphere, a conduit extending inthe-area intermediate said casings and connecting said portto the inboard end of said passageway and a discharge conduit connected to the outboard end of said passageway to receive and distribute the withdrawn fluid.

2. A double casing multiple stage centrifugal pump an outer casing having an inlet and outlet 'ior the flow offluid therethrough; an inner casing within said stuffin'gfbox; and means to obtain fluid from an intermediate pumping stage, said means comprising 'a passageway defined in said stufling box connecting thearea,intermediatefSaiil casings to the atmosphere, a said volute of' an intermeseal said shaftand said cover to diate pumping stage having a port definedthere'in connecting said intermediate armers the area intermediate said casings, a conduit extending'in .the area intermediate said casings and connecting saidport to the inboardcnd of said passageway, said conduit hav ingcoapling rneahs intermediate its ends for assembly, and .a discharge 'con-.

' duit' connected to the outboard end ofsaidpassagewayffcr 7 receiving anddistributing said withdrawn flrud, 1

References Cited'inthe file of thisjpatent; 2 UNITED "STATES PATENTS Lutz V Feb. 9, "1954 

